Very easy since the beginning of time: Summoner(s) + laggers to separate groups and generate (preferably perma)lag. Ideally duergar empire anti-paladin for combo of summon plus lag plus first initiating bash/trip, seeing hidden. Awesome if they die from a single bash (necro army, happy conjie pets) assuming they're unprepped. Roam ranking areas and Galadon/Eastern. Don't do chaotic stupid (wanted is bad, being summoned away from your gank buddies is bad, etc) and you'll be fine. Prior to road expansion 2+ bashers was enough to clean out the range at 15-25 until all were dead or quit. Still doable, albeit much harder now due to some long walks and Organia, checking which is just crazy time sink.

Ideal: Orc, duergar anti/war, necro. Much preferably a summoner in empire. Should clean out pretty much anything very fast at any rank.